Erythromycin binds reversibly to the 50S subunit of ribosomes, resulting in
the blockage of transpeptidation or translocation reactions, leading to
impaired and/or inhibited protein synthesis and, hence, to inhibited cell
growth. Colistin is an antibiotic from the group of polymyxins with a
bactericidal action against Gram-negative bacteria like E. coli, Haemophilus
and Salmonella. Since colistin is absorbed for a very small part after oral
administration only gastrointestinal indications are relevant.t